1. Field of the Invention
This invention relates to a closed loop dispensing system and more particularly to a dispensing system for dispensing corrosive liquid chemicals or dangerous medical liquid products which are typically drawn from a container such as a bottle or the like to a mixing machine or the like. Even more particularly, this invention relates to a closed loop dispensing system including a mechanical venting means for a throat plug assembly which is mounted in the throat of a liquid container.
2. Description of the Related Art
Corrosive liquid chemicals and dangerous medical liquid products are typically contained in a container such as a bottle or the like and are frequently dispensed therefrom to a mixing machine. Normally, a cap is place on the bottle with a dip tube extending therefrom downwardly into the interior of the bottle for drawing the liquid upwardly thereinto. Normally, a dispensing tube extends from the cap from a mixing machine or to some other piece of equipment which creates suction in the dispensing tube to draw the liquid from the interior of the bottle.
Applicant has previously many patented closed loop dispensing systems with improved safety means and with improved venting. For example, see U.S. Pat. No. 5,988,456.
In the prior art dispensing systems, Gortex® membranes are extended over vent openings so that air may be drawn into the interior of the bottle as liquid is being dispensed therefrom to prevent collapsing of the bottle. Although Applicant's previous inventions work extremely well, it has been found that when the liquid of the container splashes onto or comes into the Gortex® membrane the liquid may calcify on the membrane and may retard the venting of the vent opening.